Southern California -- this just in

Backers of Proposition 19 are counting on a big youth vote in their uphill battle to legalize marijuana in California.

Although polls show Proposition 19 trailing, backers told The Times' John Hoeffel and Maria L. LaGanga this week that the polls could be missing infrequent voters and young voters who might come out to the polls specifically for the measure.

"This is something tangible in their hands that they can do tomorrow that will have immediate impact," said Dale Sky Jones, a spokeswoman for the Yes on 19 campaign.

Likely voters younger than 40 are in favor of it by 48% to 37%, but older voters, who say they are more enthusiastic about voting in this election, are not. Among likely voters 65 and older, only 28% support the measure, while 59% said they were opposed, according to the poll.

According to the Times/USC poll, likely voters opposed the measure 51% to 39%.

The measure, which needs a majority vote to pass, would allow Californians who are at least 21 to grow up to 25 square feet of marijuana and possess up to an ounce. Cities and counties could authorize commercial cultivation and sales, and could impose taxes.